math.max/math.min given NaN

[David Manura <dm.lua@...>]

$ lua
Lua 5.1.3  Copyright (C) 1994-2008 Lua.org, PUC-Rio
> =math.max(0/0),math.min(0/0)
nan     nan
> =math.max(0/0,1),math.min(0/0,1)
nan     nan
> =math.max(1,0/0),math.min(1,0/0)
1       1

Is that behavior defined?  Should it be defined?